Effects of heavy rainfall on waterborne disease hospitalizations among young children in wet and dry areas of New Zealand.

Heavy rainfall is associated with increased risk of waterborne disease. However, it is not known whether the risk increment differs between wet and dry regions. We examined this question in New Zealand, which has a wide geographical variation of annual rainfall totals (10th-90th percentile difference ≥3000 mm). We conducted a nested case-crossover study within a prospective child cohort (born in 2009-2010) for assessing transient health effects when modified by longitudinal exposures to rainfall. Short-term heavy rainfall effects on hospitalizations due to enteric bacterial and viral infectious causes at lag of 0-14 days were assessed using a Cox regression model adjusted for daily temperature, relative humidity and evapotranspiration. We derived quantiles of time-weighted long-term rainfall levels at the children's homes and these were added as an interaction term to the short-term effect model. Hospitalization risks were higher two days after heavy rainfall days (hazard ratio [95% confidence interval]: 1.73 [1.10-2.70]). The lowest-observable-adverse-effect-level was detected at the 94th percentile of daily rainfall total. Hospital admissions 1-2 days after heavy rainfall increased most in locations with the lowest and highest long-term rainfall. An interaction of this kind between short-term weather and long-term climate has not been reported previously. It is relevant to climate change risk assessments given global projections of increasing intensity of precipitation, against a background of more severe, and possibly more frequent, droughts and flooding.

STROBE-Long-Term Exposure to Ambient Fine Particulate Air Pollution and Hospitalization Due to Peptic Ulcers.

Little is known about the effect of air pollution on the gastrointestinal (GI) system. We investigated the association between long-term exposures to outdoor fine particles (PM2.5) and hospitalization for peptic ulcer diseases (PUDs) in a large cohort of Hong Kong Chinese elderly.A total of 66,820 subjects aged ≥65 years who were enrolled in all 18 Government Elderly Health Service centers of Hong Kong participated in the study voluntarily between 1998 and 2001. They were prospectively followed up for more than 10 years. Annual mean exposures to PM2.5 at residence of individuals were estimated by satellite data through linkage with address details including floor level. All hospital admission records of the subjects up to December 31, 2010 were retrieved from the central database of Hospital Authority. We used Cox regression to estimate the hazard ratio (HR) for PUD hospitalization associated with PM2.5 exposure after adjustment for individual and ecological covariates.A total of 60,273 subjects had completed baseline information including medical, socio-demographic, lifestyle, and anthropometric data at recruitment. During the follow-up period, 1991 (3.3%) subjects had been hospitalized for PUD. The adjusted HR for PUD hospitalization per 10 µg/m of PM2.5 was 1.18 (95% confidence interval: 1.02-1.36, P = 0.02). Further analysis showed that the associations with PM2.5 were significant for gastric ulcers (HR 1.29; 1.09-1.53, P = 0.003) but not for duodenal ulcers (HR 0.98; 0.78 to 1.22, P = 0.81).Long-term exposures to PM2.5 were associated with PUD hospitalization in elder population. The mechanism underlying the PM2.5 in the development of gastric ulcers warrants further research.

Health impact assessment of exposure to fine particulate matter based on satellite and meteorological information.

Air pollution in China, especially in the Pearl River Delta (PRD) region, has drastically increased in recent years. We modelled annual mean ground-level PM2.5 concentrations based on worldwide satellite information and meteorological data from 40 cities outside the PRD. The model of PM2.5 concentration (R = 0.845) was best explained by aerosol optical thickness (43.8%). We validated the spatial-temporal dimensions of the model and estimated that the annual mean PM2.5 concentration in PRD ranged between 22 and 65 µg m(-3). Then we used meta-analysis to obtain the pooled excess risks of mortality in China and assessed the health impacts. We found an inverse association between short-term excess risks of mortality and annual mean PM2.5 concentrations. Based on the above models and analyses, the associated excess deaths for all-cause and cardiopulmonary diseases were 3386 and 2639 respectively. The corresponding risk-standardized excess death rates were 2006 and 1069 per million people.

A method to derive the relationship between the annual and short-term air quality limits--analysis using the WHO Air Quality Guidelines for health protection.

The World Health Organization (WHO) Air Quality Guidelines (AQG) were launched in 2006, but gaps remain in evidence on health impacts and relationships between short-term and annual AQG needed for health protection. We tested whether relationships between WHO short-term and annual AQG for particulates (PM10 and PM2.5) and nitrogen dioxide (NO2) are concordant worldwide and derived the annual limits for sulfur dioxide (SO2) and ozone (O3) based on the short-term AQG. We obtained air pollutant data over seven years (2004-2010) in seven cities from Asia-Pacific, North America and Europe. Based on probability distribution concept using maximum as the short-term limit and arithmetic mean as the annual limit, we developed a new method to derive limit value one from another in each paired limits for each pollutant with capability to account for allowable exceedances. We averaged the limit derived each year for each city, then used meta-analysis to pool the limit values in all cities. Pooled mean short-term limit for NO2 (140.5µg/m(3) [130.6-150.4]) was significantly lower than the WHO AQG of 200µg/m(3) while for PM10 (46.4µg/m(3) [95CI:42.1-50.7]) and PM2.5 (28.6µg/m(3) [24.5-32.6]) were not significantly different from the WHO AQG of 50 and 25µg/m(3) respectively. Pooled mean annual limits for SO2 and O3 were 4.6µg/m(3) [3.7-5.5] and 27.0µg/m(3) [21.7-32.2] respectively. Results were robust in various sensitivity analyses. The distribution relationships between the current WHO short-term and annual AQG are supported by empirical data from seven cities for PM10 and PM2.5, but not for NO2. The short-term AQG for NO2 should be lowered for concordance with the selected annual AQG for health protection.

Thermal stress associated mortality risk and effect modification by sex and obesity in an elderly cohort of Chinese in Hong Kong.

We assessed the effects of apparent temperature (AT) on mortality and the effect modifications attributable to individual characteristics in Hong Kong with subtropical climate conditions. Two datasets are used for analyses: one from mortality data of the general elderly population in 1998-2009; the other from an elderly cohort with 66,820 subjects recruited in 1998-2001 with mortality outcomes followed up until 2009. We found that AT below 20.8 °C was associated with an increase in mortality risk of 1.99% (95% confidence interval: 0.64%, 2.64%) for all causes, 2.48% (0.57%, 4.36%) for cardiovascular disease, and 3.19% (0.59%, 5.73%) for respiratory disease for every 1 °C decrease in AT over the following 3 days. The associations were modified by sex and body mass index, in particular stronger associations were observed for females and for obese subjects.

Meta-analysis of adverse health effects due to air pollution in Chinese populations.

BACKGROUND: Pooled estimates of air pollution health effects are important drivers of environmental risk communications and political willingness. In China, there is a lack of review studies to provide such estimates for health impact assessments. METHODS: We systematically searched the MEDLINE database using keywords of 80 major Chinese cities in Mainland China, Hong Kong and Taiwan on 30 June 2012, yielding 350 abstracts with 48 non-duplicated reports either in English or Chinese after screening. We pooled the relative risks (RR) per 10 µg/m3 of particulate matter (PM10), nitrogen dioxide (NO2), sulphur dioxide (SO2) and ozone (O3). RESULTS: For short-term effects, the pooled RR (p<0.05) ranges were: 1.0031 (PM10) to 1.0140 (NO2) for all-cause mortality, 1.0034 (cardiopulmonary, PM10) to 1.0235 (influenza and pneumonia, SO2) for 9 specific-causes mortality, 1.0021 (cardiovascular, PM10) to 1.0162 (asthma, O3) for 5 specific-causes hospital admissions. For birth outcomes, the RR (p<0.05) ranged from 1.0051 (stillbirth, O3) to 1.1189 (preterm-birth, SO2) and for long-term effect on mortality from 1.0150 (respiratory, SO2) to 1.0297 (respiratory, NO2). Publication bias was absent (Egger test: p=0.326 to 0.624). Annual PM10 and NO2 concentrations were inversely associated with RR of mortality (p=0.017-0.028). CONCLUSIONS: Evidence on short-term effects of air pollution is consistent and sufficient for health impact assessment but that on long-term effects is still insufficient.

Lung function and exposure to workplace second-hand smoke during exemptions from smoking ban legislation: an exposure-response relationship based on indoor PM2.5 and urinary cotinine levels.

BACKGROUND: The effects of workplace second-hand smoke (SHS) on lung function remain uncertain because of a lack of objective measures for SHS exposures. OBJECTIVE: To determine whether an exposure-response association exists between lung function and two different markers of SHS based on indoor fine particulate (PM(2.5)) and urinary cotinine levels in non-smoking catering workers. DESIGN: A cross-sectional study during a 1.5-year exemption of licensed catering premises from smoke-free legislation. Participants 186 non-smoking catering workers aged 18-65 years in Hong Kong were recruited. A declared non-smoking status was accepted in workers with exhaled breath carbon monoxide levels <6 ppm and urinary cotinine levels <100 ng/ml. MAIN OUTCOME MEASURES: Lung function measures of forced expiratory volume in 1s (FEV(1) in litres), forced vital capacity (FVC in litres) and forced expiratory flow as 25-75% of FVC (FEF(25-75) in l/s) were recorded. RESULTS: Indoor fine particulate (PM(2.5)) concentrations were 4.4 times as high in smoking premises (267.9 µg/m(3)) than in non-smoking premises (60.3 µg/m(3)) and were strongly associated with the probability of permitted smoking (R(2)=0.99). Smoking was the dominant source of particulates (R(2)=0.66). Compared with workers exposed to the lowest indoor PM(2.5) stratum (<25 µg/m(3)), lung function was lower in the three higher PM(2.5) strata (25-75, 75-175, >175 µg/m(3)) with FEV(1) -0.072 (95% CI -0.123 to -0.021), -0.078 (95% CI -0.132 to -0.024), -0.101 (95% CI -0.187 to -0.014); FEF(25-75) -0.368 (95% CI -0.660 to -0.077), -0.489 (95% CI -0.799 to -0.179), -0.597 (95% CI -0.943 to -0.251); and FEV(1)/FVC (%) -2.9 (95% CI -4.8 to -1.0), -3.2 (95% CI -5.1 to -1.4) and -4.4 (95% CI -7.4 to -1.3), respectively. Urinary cotinine was associated positively with indoor PM(2.5) but negatively with lung function. Consistently lower values for lung function per unit increase of indoor PM(2.5) were found. CONCLUSION: Lung function is inversely associated with workplace SHS. Workplace exemptions and delays in implementing smoke-free policies and current moves to relax legislation are a major threat to the health of workers.

Weight misperception and psychosocial health in normal weight Chinese adolescents.

OBJECTIVE: To investigate the association between weight misperception and psychosocial health problems among normal weight Chinese adolescent boys and girls. METHODS: In the Youth Smoking Survey 2003-04, 20 677 normal weight students aged 11-18 years from 85 randomly selected schools throughout Hong Kong were analysed. Students who perceived themselves as very thin, thin, fat or very fat were classified as having weight misperception in contrast to the reference group who correctly perceived themselves as normal weight. Psychosocial health outcomes included headache, feeling stressful, feeling depressed, poorer appetite, sleepless at night, having nightmares and less confidence in getting along with friends. Logistic regression yielded adjusted odds ratios (ORs) for each outcome by weight misperception in boys and girls separately. RESULTS: In girls, misperceived fatness was associated with all outcomes, while misperceived thinness was associated with poorer appetite and less confidence. Boys who misperceived themselves as very thin or fat had greater odds of all outcomes except having nightmares. In general, greater ORs were observed for misperceived fatness than thinness in girls, but similar ORs were observed in boys. Misperceived thinness and fatness accounted for 0.6% to 45.1% of the psychosocial health problems in adolescents. CONCLUSIONS: Normal weight adolescents with weight misperception were more likely to have psychosocial health problems, and the associations were stronger for extreme misperceptions (i.e., very fat or very thin) in both boys and girls.

'Carcinogens in a puff': smoking in Hong Kong movies.

Smoking scenes in movies, exploited by the tobacco industry to circumvent advertisement bans, are linked to adolescent smoking. Recently, a Hong Kong romantic comedy Love in a puff put smoking at centre stage, with numerous smoking scenes and words that glamourise smoking. Although WHO has issued guidelines on reducing the exposure of children to smoking in movies, none is adopted in Hong Kong. Comprehensive tobacco control strategies are urgently needed to protect young people in Hong Kong from cigarette promotion in movies.

Exposure to secondhand smoke and academic performance in non-smoking adolescents.

OBJECTIVE: To study the association between exposure to secondhand smoke (SHS) and academic performance in non-smoking adolescents. STUDY DESIGN: A questionnaire survey of 23 052 non-smoking students aged 11 to 20 years was conducted. Information on academic performance, number of days of SHS exposure per week at home and outside the home, number of smokers at home and their relationship with the student, and sociodemographic characteristics was recorded. RESULTS: Students exposed to SHS at home 1 to 4 and 5 to 7 days per week were 14% (95% confidence interval, 5%-25%) and 28% (15%-41%) more likely, respectively, to report poor academic performance compared with students who were not exposed to SHS. Living with one, two, and ≥ 3 smokers, compared with no smoker, was also associated with 10% (0.1%-20%), 43% (23%-65%) and 87% (54%-127%), respectively, higher odds of poor academic performance (P for trend <.001). The greatest excess risks were observed with SHS exposure from co-residing non-relatives, followed by siblings, visitors, co-residing grandparents and relatives, and parents. CONCLUSION: SHS exposure is associated linearly with poor academic performance in non-smoking adolescents, and the effect of SHS exposure at home is stronger from smokers other than the parents.

Exposure to particulate air pollution at different living locations and respiratory symptoms in Hong Kong--an application of satellite information.

Respiratory ill-health effects due to particulate air exposure at different geographical locations in Hong Kong that aggregate individual living locations were estimated based on satellite information. We assessed the presence of respiratory symptoms of a frequent cough or sputum in school students aged 11-20 years old (n = 9,881). Daily particulate air pollution levels at students' living locations were derived from the surface extinction coefficients measured by satellite and measurements from the air pollutant monitoring stations at ground level. Adjusted odds ratio (OR) [95% CI] of respiratory symptoms was 1.047 [1.005, 1.091] per 10 microg m(-3) increase in PM(10) concentration. Specificity tests showed that adjusted OR of having other symptoms is not significant (p = 0.20-0.94). Exposures to PM(10) at different geographical locations is associated with increased odds of having respiratory symptoms (cough or sputum) but not with other symptoms unrelated to air pollution.

Secondhand smoke and respiratory symptoms among adolescent current smokers.

OBJECTIVE: No study has ever reported the association between persistent respiratory symptoms and exposure to secondhand smoke (SHS) in adolescent smokers. The impact of SHS exposure on child health could be largely underestimated by not taking into account such effects. We investigated the association between exposure to SHS and respiratory symptoms among adolescent current smokers. METHODS: A total of 32506 students aged 11 to 20 years from 85 randomly selected secondary schools in Hong Kong completed a self-administered questionnaire that included persistent respiratory symptoms (for 3 consecutive months in the past 12 months), number of days of SHS exposure per week at home and outside home, smoking status, amount of active smoking, and other basic demographic characteristics and socioeconomic status. RESULTS: Adolescent current smokers who were exposed to SHS at home 1 to 4 and 5 to 7 days/wk were 50% (95% confidence interval [CI]: 3%-121%) and 77% (95% CI: 5%-199%) more likely, respectively, to report respiratory symptoms compared with those who were unexposed (P = .01 for trend). The corresponding figures for exposure outside home were 41% (95% CI: 3%-94%) and 85% (95% CI: 31%-161%; P = .004 for trend). Such associations were also observed among never-smokers, but they were weaker than those among current smokers (P < .01 for interaction). CONCLUSIONS: This is the first evidence that SHS exposure is associated with increased risks for persistent respiratory symptoms among adolescent current smokers. Health promotion programs should aim at SHS reduction as well as smoking cessation among adolescent smokers.

Is exercise protective against influenza-associated mortality?

BACKGROUND: Little is known about the effect of physical exercise on influenza-associated mortality. METHODS AND FINDINGS: We collected information about exercise habits and other lifestyles, and socioeconomic and demographic status, the underlying cause of death of 24,656 adults (21% aged 30-64, 79% aged 65 or above) who died in 1998 in Hong Kong, and the weekly proportion of specimens positive for influenza A (H3N1 and H1N1) and B isolations during the same period. We assessed the excess risks (ER) of influenza-associated mortality due to all-natural causes, cardiovascular diseases, or respiratory disease among different levels of exercise: never/seldom (less than once per month), low/moderate (once per month to three times per week), and frequent (four times or more per week) by Poisson regression. We also assessed the differences in ER between exercise groups by case-only logistic regression. For all the mortality outcomes under study in relation to each 10% increase in weekly proportion of specimens positive for influenza A+B, never/seldom exercise (as reference) was associated with 5.8% to 8.5% excess risks (ER) of mortality (P<0.0001), while low/moderate exercise was associated with ER which were 4.2% to 6.4% lower than those of the reference (P<0.001 for all-natural causes; P = 0.001 for cardiovascular; and P = 0.07 for respiratory mortality). Frequent exercise was not different from the reference (change in ER -0.8% to 1.7%, P = 0.30 to 0.73). CONCLUSION: When compared with never or seldom exercise, exercising at low to moderate frequency is beneficial with lower influenza-associated mortality.